The care of the colostomy patient should be based on an understanding of the absorptive capacity of the residual colon proximal to the colostomy. The absorptive capacity of such patients for water and sodium is not known, although these rates of absorption are probably the most important determinants of stool volume and consistency which affect colostomy care. It is proposed to determine the absorptive capacity for sodium and water by colostomy patients on varying sodium intakes by external balance studies, and to determine the absorptive capacity of the right and left colon in intact man and in colostomy patients by direct colon perfusion studies. All studies will be repeated over a period of one to three years to determine if the intestinal remnant increases its functional capacity to compensate for the lost colon. The studies may provide information which will improve colostomy diets, as well as information on segmental colonic absorptive capacity important to an understanding of segmental colon disease.